Objective To simulate the orthodontic tooth movement (OTM) after corticotomy in rat and analyze its effects on mechanical distribution in dentoalveolar structures.Methods 3D finite element model of corticotomy-facilitated OTM in rat was established and the circumscribing corticotomy approach was simulated. The periodontal ligament (PDL) and alveolar bone around the mesial root were partitioned according to direction of the orthodontic load and corresponding part of the root. The initial displacement of the first molar and segmented alveolar bone as well as the stress and strain in PDL and alveolar bone were calculated. Results The first molar presented a tipping movement and the distal cusp showed the maximum displacement. Corticotomy could increase the relative displacement of bone segment. The maximum principal strain in PDL concentrated on the mesial and distal cervical region, while the minimum principal strain concentrated on the distal apical region. Corticotomy could change the distribution and magnitude of the maximum and minimum principal strain in PDL and Von Mises stress in alveolar bone. Conclusions Corticotomy can affect the mechanical distribution of orthodontic force in tooth and periodontal tissues around, and hence facilitate regional bone remodeling to realize rapid OTM. The research findings contribute to understanding the mechanism of corticotomy to facilitate OTM from the aspect of biomechanics.